European Mountain-ash Sorbus aucuparia
Family: Rosaceae (Rose)
Branching: Alternate

These small northern trees are not actually Ashes, but members of the Rose family.  There are two native species: American (S. americana) and Showy (S. decora), though they don't seem to be easily seperated, especially in the winter.  One introduced species, European (S. aucuparia), is commonly planted in cities, and is the most likely to be found in southern Ontario.  All three closely resemble each other in size and form, especially the two native species.  The main differences are in the buds, which are hairy for European Mountain-ash and shiny and resinous for the native species.  The buds are fairly large, especially the end bud.  The bark is often marked with horizontal slits similar to cherries and birches.  

The winter twig and end bud of European Mountain-ash

Another view of the bud.  Notice the white-wooly hair.

Winter twig and buds

The bark is often marked with horizontal lenticels

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copyright © 2008 Josh Sayers
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